5 files changed, 245 insertions, 101 deletions

diff --git a/lib/CodeGen/IfConversion.cpp b/lib/CodeGen/IfConversion.cpp
index 38fce9b435..a83d7f1fcc 100644
--- a/lib/CodeGen/IfConversion.cpp
+++ b/lib/CodeGen/IfConversion.cpp
@@ -849,7 +849,8 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) {
   }
 
   if (Kind == ICSimpleFalse)
-    TII->ReverseBranchCondition(Cond);
+    if (TII->ReverseBranchCondition(Cond))
+      assert(false && "Unable to reverse branch condition!");
 
   if (CvtBBI->BB->pred_size() > 1) {
     BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
@@ -914,21 +915,23 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
   }
 
   if (Kind == ICTriangleFalse || Kind == ICTriangleFRev)
-    TII->ReverseBranchCondition(Cond);
+    if (TII->ReverseBranchCondition(Cond))
+      assert(false && "Unable to reverse branch condition!");
 
   if (Kind == ICTriangleRev || Kind == ICTriangleFRev) {
-    ReverseBranchCondition(*CvtBBI);
-    // BB has been changed, modify its predecessors (except for this
-    // one) so they don't get ifcvt'ed based on bad intel.
-    for (MachineBasicBlock::pred_iterator PI = CvtBBI->BB->pred_begin(),
-           E = CvtBBI->BB->pred_end(); PI != E; ++PI) {
-      MachineBasicBlock *PBB = *PI;
-      if (PBB == BBI.BB)
-        continue;
-      BBInfo &PBBI = BBAnalysis[PBB->getNumber()];
-      if (PBBI.IsEnqueued) {
-        PBBI.IsAnalyzed = false;
-        PBBI.IsEnqueued = false;
+    if (ReverseBranchCondition(*CvtBBI)) {
+      // BB has been changed, modify its predecessors (except for this
+      // one) so they don't get ifcvt'ed based on bad intel.
+      for (MachineBasicBlock::pred_iterator PI = CvtBBI->BB->pred_begin(),
+             E = CvtBBI->BB->pred_end(); PI != E; ++PI) {
+        MachineBasicBlock *PBB = *PI;
+        if (PBB == BBI.BB)
+          continue;
+        BBInfo &PBBI = BBAnalysis[PBB->getNumber()];
+        if (PBBI.IsEnqueued) {
+          PBBI.IsAnalyzed = false;
+          PBBI.IsEnqueued = false;
+        }
       }
     }
   }
@@ -1028,7 +1031,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
   BBInfo *BBI1 = &TrueBBI;
   BBInfo *BBI2 = &FalseBBI;
   SmallVector<MachineOperand, 4> RevCond(BBI.BrCond.begin(), BBI.BrCond.end());
-  TII->ReverseBranchCondition(RevCond);
+  if (TII->ReverseBranchCondition(RevCond))
+    assert(false && "Unable to reverse branch condition!");
   SmallVector<MachineOperand, 4> *Cond1 = &BBI.BrCond;
   SmallVector<MachineOperand, 4> *Cond2 = &RevCond;
 
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 05db7cb886..ebf9eecf20 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -5100,6 +5100,71 @@ SDValue X86TargetLowering::LowerBRCOND(SDValue Op, SelectionDAG &DAG) {
       Cond = Cmp;
       addTest = false;
     }
+  // Also, recognize the pattern generated by an FCMP_UNE. We can emit
+  // two branches instead of an explicit OR instruction with a
+  // separate test.
+  } else if (Cond.getOpcode() == ISD::OR &&
+             Cond.hasOneUse() &&
+             Cond.getOperand(0).getOpcode() == X86ISD::SETCC &&
+             Cond.getOperand(0).hasOneUse() &&
+             Cond.getOperand(1).getOpcode() == X86ISD::SETCC &&
+             Cond.getOperand(1).hasOneUse()) {
+    SDValue Cmp = Cond.getOperand(0).getOperand(1);
+    unsigned Opc = Cmp.getOpcode();
+    if (Cmp == Cond.getOperand(1).getOperand(1) &&
+        (Opc == X86ISD::CMP ||
+         Opc == X86ISD::COMI ||
+         Opc == X86ISD::UCOMI)) {
+      CC = Cond.getOperand(0).getOperand(0);
+      Chain = DAG.getNode(X86ISD::BRCOND, Op.getValueType(),
+                          Chain, Dest, CC, Cmp);
+      CC = Cond.getOperand(1).getOperand(0);
+      Cond = Cmp;
+      addTest = false;
+    }
+  // Also, recognize the pattern generated by an FCMP_OEQ. We can emit
+  // two branches instead of an explicit AND instruction with a
+  // separate test. However, we only do this if this block doesn't
+  // have a fall-through edge, because this requires an explicit
+  // jmp when the condition is false.
+  } else if (Cond.getOpcode() == ISD::AND &&
+             Cond.hasOneUse() &&
+             Cond.getOperand(0).getOpcode() == X86ISD::SETCC &&
+             Cond.getOperand(0).hasOneUse() &&
+             Cond.getOperand(1).getOpcode() == X86ISD::SETCC &&
+             Cond.getOperand(1).hasOneUse()) {
+    SDValue Cmp = Cond.getOperand(0).getOperand(1);
+    unsigned Opc = Cmp.getOpcode();
+    if (Cmp == Cond.getOperand(1).getOperand(1) &&
+        (Opc == X86ISD::CMP ||
+         Opc == X86ISD::COMI ||
+         Opc == X86ISD::UCOMI) &&
+        Op.getNode()->hasOneUse()) {
+      X86::CondCode CCode =
+        (X86::CondCode)Cond.getOperand(0).getConstantOperandVal(0);
+      CCode = X86::GetOppositeBranchCondition(CCode);
+      CC = DAG.getConstant(CCode, MVT::i8);
+      SDValue User = SDValue(*Op.getNode()->use_begin(), 0);
+      // Look for an unconditional branch following this conditional branch.
+      // We need this because we need to reverse the successors in order
+      // to implement FCMP_OEQ.
+      if (User.getOpcode() == ISD::BR) {
+        SDValue FalseBB = User.getOperand(1);
+        SDValue NewBR =
+          DAG.UpdateNodeOperands(User, User.getOperand(0), Dest);
+        assert(NewBR == User);
+        Dest = FalseBB;
+
+        Chain = DAG.getNode(X86ISD::BRCOND, Op.getValueType(),
+                            Chain, Dest, CC, Cmp);
+        X86::CondCode CCode =
+          (X86::CondCode)Cond.getOperand(1).getConstantOperandVal(0);
+        CCode = X86::GetOppositeBranchCondition(CCode);
+        CC = DAG.getConstant(CCode, MVT::i8);
+        Cond = Cmp;
+        addTest = false;
+      }
+    }
   }
 
   if (addTest) {
@@ -5107,7 +5172,7 @@ SDValue X86TargetLowering::LowerBRCOND(SDValue Op, SelectionDAG &DAG) {
     Cond= DAG.getNode(X86ISD::CMP, MVT::i32, Cond, DAG.getConstant(0, MVT::i8));
   }
   return DAG.getNode(X86ISD::BRCOND, Op.getValueType(),
-                     Chain, Op.getOperand(2), CC, Cond);
+                     Chain, Dest, CC, Cond);
 }
 
 
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 84e113f885..2db1448fd7 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -1455,88 +1455,101 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
                                  MachineBasicBlock *&TBB,
                                  MachineBasicBlock *&FBB,
                                  SmallVectorImpl<MachineOperand> &Cond) const {
-  // If the block has no terminators, it just falls into the block after it.
+  // Start from the bottom of the block and work up, examining the
+  // terminator instructions.
   MachineBasicBlock::iterator I = MBB.end();
-  if (I == MBB.begin() || !isBrAnalysisUnpredicatedTerminator(--I, *this))
-    return false;
-
-  // Get the last instruction in the block.
-  MachineInstr *LastInst = I;
-  
-  // If there is only one terminator instruction, process it.
-  if (I == MBB.begin() || !isBrAnalysisUnpredicatedTerminator(--I, *this)) {
-    if (!LastInst->getDesc().isBranch())
+  while (I != MBB.begin()) {
+    --I;
+    // Working from the bottom, when we see a non-terminator
+    // instruction, we're done.
+    if (!isBrAnalysisUnpredicatedTerminator(I, *this))
+      break;
+    // A terminator that isn't a branch can't easily be handled
+    // by this analysis.
+    if (!I->getDesc().isBranch())
       return true;
-    
-    // If the block ends with a branch there are 3 possibilities:
-    // it's an unconditional, conditional, or indirect branch.
-    
-    if (LastInst->getOpcode() == X86::JMP) {
-      TBB = LastInst->getOperand(0).getMBB();
-      return false;
+    // Handle unconditional branches.
+    if (I->getOpcode() == X86::JMP) {
+      // If the block has any instructions after a JMP, delete them.
+      while (next(I) != MBB.end())
+        next(I)->eraseFromParent();
+      Cond.clear();
+      FBB = 0;
+      // Delete the JMP if it's equivalent to a fall-through.
+      if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
+        TBB = 0;
+        I->eraseFromParent();
+        I = MBB.end();
+        continue;
+      }
+      // TBB is used to indicate the unconditinal destination.
+      TBB = I->getOperand(0).getMBB();
+      continue;
     }
-    X86::CondCode BranchCode = GetCondFromBranchOpc(LastInst->getOpcode());
+    // Handle conditional branches.
+    X86::CondCode BranchCode = GetCondFromBranchOpc(I->getOpcode());
     if (BranchCode == X86::COND_INVALID)
       return true;  // Can't handle indirect branch.
-
-    // Otherwise, block ends with fall-through condbranch.
-    TBB = LastInst->getOperand(0).getMBB();
-    Cond.push_back(MachineOperand::CreateImm(BranchCode));
-    return false;
-  }
-  
-  // Get the instruction before it if it's a terminator.
-  MachineInstr *SecondLastInst = I;
-  
-  // If there are three terminators, we don't know what sort of block this is.
-  if (SecondLastInst && I != MBB.begin() &&
-      isBrAnalysisUnpredicatedTerminator(--I, *this))
-    return true;
-
-  // If the block ends with X86::JMP and a conditional branch, handle it.
-  X86::CondCode BranchCode = GetCondFromBranchOpc(SecondLastInst->getOpcode());
-  if (BranchCode != X86::COND_INVALID && LastInst->getOpcode() == X86::JMP) {
-    TBB = SecondLastInst->getOperand(0).getMBB();
-    Cond.push_back(MachineOperand::CreateImm(BranchCode));
-    FBB = LastInst->getOperand(0).getMBB();
-    return false;
-  }
-
-  // If the block ends with two X86::JMPs, handle it.  The second one is not
-  // executed, so remove it.
-  if (SecondLastInst->getOpcode() == X86::JMP && 
-      LastInst->getOpcode() == X86::JMP) {
-    TBB = SecondLastInst->getOperand(0).getMBB();
-    I = LastInst;
-    I->eraseFromParent();
-    return false;
+    // Working from the bottom, handle the first conditional branch.
+    if (Cond.empty()) {
+      FBB = TBB;
+      TBB = I->getOperand(0).getMBB();
+      Cond.push_back(MachineOperand::CreateImm(BranchCode));
+      continue;
+    }
+    // Handle subsequent conditional branches. Only handle the case
+    // where all conditional branches branch to the same destination
+    // and their condition opcodes fit one of the special
+    // multi-branch idioms.
+    assert(Cond.size() == 1);
+    assert(TBB);
+    // Only handle the case where all conditional branches branch to
+    // the same destination.
+    if (TBB != I->getOperand(0).getMBB())
+      return true;
+    X86::CondCode OldBranchCode = (X86::CondCode)Cond[0].getImm();
+    // If the conditions are the same, we can leave them alone.
+    if (OldBranchCode == BranchCode)
+      continue;
+    // If they differ, see if they fit one of the known patterns.
+    // Theoretically we could handle more patterns here, but
+    // we shouldn't expect to see them if instruction selection
+    // has done a reasonable job.
+    if ((OldBranchCode == X86::COND_NP &&
+         BranchCode == X86::COND_E) ||
+        (OldBranchCode == X86::COND_E &&
+         BranchCode == X86::COND_NP))
+      BranchCode = X86::COND_NP_OR_E;
+    else if ((OldBranchCode == X86::COND_P &&
+              BranchCode == X86::COND_NE) ||
+             (OldBranchCode == X86::COND_NE &&
+              BranchCode == X86::COND_P))
+      BranchCode = X86::COND_NE_OR_P;
+    else
+      return true;
+    // Update the MachineOperand.
+    Cond[0].setImm(BranchCode);
   }
 
-  // Otherwise, can't handle this.
-  return true;
+  return false;
 }
 
 unsigned X86InstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator I = MBB.end();
-  if (I == MBB.begin()) return 0;
-  --I;
-  if (I->getOpcode() != X86::JMP && 
-      GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID)
-    return 0;
-  
-  // Remove the branch.
-  I->eraseFromParent();
-  
-  I = MBB.end();
-  
-  if (I == MBB.begin()) return 1;
-  --I;
-  if (GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID)
-    return 1;
+  unsigned Count = 0;
+
+  while (I != MBB.begin()) {
+    --I;
+    if (I->getOpcode() != X86::JMP &&
+        GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID)
+      break;
+    // Remove the branch.
+    I->eraseFromParent();
+    I = MBB.end();
+    ++Count;
+  }
   
-  // Remove the branch.
-  I->eraseFromParent();
-  return 2;
+  return Count;
 }
 
 static const MachineInstrBuilder &X86InstrAddOperand(MachineInstrBuilder &MIB,
@@ -1571,23 +1584,43 @@ X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
   assert((Cond.size() == 1 || Cond.size() == 0) &&
          "X86 branch conditions have one component!");
 
-  if (FBB == 0) { // One way branch.
-    if (Cond.empty()) {
-      // Unconditional branch?
-      BuildMI(&MBB, get(X86::JMP)).addMBB(TBB);
-    } else {
-      // Conditional branch.
-      unsigned Opc = GetCondBranchFromCond((X86::CondCode)Cond[0].getImm());
-      BuildMI(&MBB, get(Opc)).addMBB(TBB);
-    }
+  if (Cond.empty()) {
+    // Unconditional branch?
+    assert(!FBB && "Unconditional branch with multiple successors!");
+    BuildMI(&MBB, get(X86::JMP)).addMBB(TBB);
     return 1;
   }
-  
-  // Two-way Conditional branch.
-  unsigned Opc = GetCondBranchFromCond((X86::CondCode)Cond[0].getImm());
-  BuildMI(&MBB, get(Opc)).addMBB(TBB);
-  BuildMI(&MBB, get(X86::JMP)).addMBB(FBB);
-  return 2;
+
+  // Conditional branch.
+  unsigned Count = 0;
+  X86::CondCode CC = (X86::CondCode)Cond[0].getImm();
+  switch (CC) {
+  case X86::COND_NP_OR_E:
+    // Synthesize NP_OR_E with two branches.
+    BuildMI(&MBB, get(X86::JNP)).addMBB(TBB);
+    ++Count;
+    BuildMI(&MBB, get(X86::JE)).addMBB(TBB);
+    ++Count;
+    break;
+  case X86::COND_NE_OR_P:
+    // Synthesize NE_OR_P with two branches.
+    BuildMI(&MBB, get(X86::JNE)).addMBB(TBB);
+    ++Count;
+    BuildMI(&MBB, get(X86::JP)).addMBB(TBB);
+    ++Count;
+    break;
+  default: {
+    unsigned Opc = GetCondBranchFromCond(CC);
+    BuildMI(&MBB, get(Opc)).addMBB(TBB);
+    ++Count;
+  }
+  }
+  if (FBB) {
+    // Two-way Conditional branch. Insert the second branch.
+    BuildMI(&MBB, get(X86::JMP)).addMBB(FBB);
+    ++Count;
+  }
+  return Count;
 }
 
 bool X86InstrInfo::copyRegToReg(MachineBasicBlock &MBB,
@@ -2372,6 +2405,8 @@ bool X86InstrInfo::
 ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
   assert(Cond.size() == 1 && "Invalid X86 branch condition!");
   X86::CondCode CC = static_cast<X86::CondCode>(Cond[0].getImm());
+  if (CC == X86::COND_NE_OR_P || CC == X86::COND_NP_OR_E)
+    return true;
   Cond[0].setImm(GetOppositeBranchCondition(CC));
   return false;
 }
diff --git a/lib/Target/X86/X86InstrInfo.h b/lib/Target/X86/X86InstrInfo.h
index 0a0de5e2de..17be894a88 100644
--- a/lib/Target/X86/X86InstrInfo.h
+++ b/lib/Target/X86/X86InstrInfo.h
@@ -44,6 +44,15 @@ namespace X86 {
     COND_O  = 13,
     COND_P  = 14,
     COND_S  = 15,
+
+    // Artificial condition codes. These are used by AnalyzeBranch
+    // to indicate a block terminated with two conditional branches to
+    // the same location. This occurs in code using FCMP_OEQ or FCMP_UNE,
+    // which can't be represented on x86 with a single condition. These
+    // are never used in MachineInstrs.
+    COND_NE_OR_P,
+    COND_NP_OR_E,
+
     COND_INVALID
   };
     
diff --git a/test/CodeGen/X86/isint.ll b/test/CodeGen/X86/isint.ll
new file mode 100644
index 0000000000..9915bfa8d6
--- /dev/null
+++ b/test/CodeGen/X86/isint.ll
@@ -0,0 +1,31 @@
+; llvm-as < %s | llc -march=x86 > %t
+; not grep cmp %t
+; not grep xor %t
+; grep jne %t | count 1
+; grep jp %t | count 1
+; grep setnp %t | count 1
+; grep sete %t | count 1
+; grep and %t | count 1
+; grep cvt %t | count 4
+
+define i32 @isint_return(double %d) nounwind {
+  %i = fptosi double %d to i32
+  %e = sitofp i32 %i to double
+  %c = fcmp oeq double %d, %e
+  %z = zext i1 %c to i32
+  ret i32 %z
+}
+
+declare void @foo()
+
+define void @isint_branch(double %d) nounwind {
+  %i = fptosi double %d to i32
+  %e = sitofp i32 %i to double
+  %c = fcmp oeq double %d, %e
+  br i1 %c, label %true, label %false
+true:
+  call void @foo()
+  ret void
+false:
+  ret void
+}